Process Safety: Walk The Line

Company-wide initiative eliminates operator line-up errors

By Jerry J. Forest, Celanese

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During an operation to return a filter back to service, a hydrocarbon spill resulted in a reportable quantity release and an API RP-754 Tier 1 process safety incident. The investigation found that the operator neglected to close the downstream bleed valve, causing the release. Corrective action included disciplining the operator.

Does this scenario sound familiar? It likely will. Industry data indicate that greater than 20% of loss of primary containment (LOPC) incidents stem from a few causes: valves left open, open-ended lines on energized pipe and vessels, and line-up errors. More than 10% of these events occur during equipment startup [1].

Blaming an operator when line-up errors occur seems easy but doesn’t address the underlying problem. We never will eliminate these human-error causes of process safety incidents until we go beyond simply noting “operator left valve open” and answer the question “Why did the operator leave the valve open?”

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Analysis of process safety incident data at Celanese indicated that almost half of the incident causes related to conduct of operations — i.e., the management systems in place to ensure operators perform their tasks correctly [2]; a majority of these were line-up errors. The most common operating mode during the incidents is startup or returning equipment to service following maintenance. Recognizing that the most fundamental task operators perform is to line-up equipment, Celanese developed the “Walk the Line” program. It is based on a belief that the operators must know with 100% certainty where energy will flow each time a change is made in the processing unit. The premise of the program is that we can change behavior by providing a culture of setting the expectation for accuracy in line-up, and giving operators the tools to ensure accuracy in line-up.

An Essential First Step

A pre-condition for Walk the Line is understanding the causes of operator line-up error. This becomes problematic if investigations stop at “operator left valve open” as the cause. As Celanese developed our Walk the Line program, it became clear that we first must improve the quality of our incident investigation process and root cause analysis (RCA). We approached this in two ways. After identifying the line-up error incidents, we asked each site to analyze its near-miss and incident data to the best of its ability to identify why the errors occurred. In addition to this analysis, we completed a global incident investigation management-training program that targeted improving the quality of the application of RCA methodology to give greater consideration to human factor causes. We instituted a practice of reviewing all Tier 1 and Tier 2 RCAs to normalize the quality of cause maps and corrective actions. The metric we chose to measure effectiveness of the training and RCA reviews is “lack of information for cause.” Figure 1 shows the improvement trend since these practices were initiated, with 2011 as the base comparison year.

As our RCAs improved, we were able to characterize the causes of line-up errors as: expectation for energy control not set, lack of continuity of operations, and deficiencies with operational readiness. Walk the Line was adopted as a readily recognizable way to raise awareness in these three areas.

Celanese implemented Walk the Line in 2013 and achieved immediate results. Since implementation, LOPC incidents related to operator line-up have fallen 30% per year on average. Figure 2 illustrates these results. The fact some incident causes persist highlights it may take up to five years to effectively ingrain a practice into the culture for lasting change.

Tailored Implementation

On reviewing the causal data, it was apparent that each site had unique gaps falling within the three categories. The approach therefore was to focus on culture change at the corporate level, provide the operational discipline tools to address operational continuity, and the operational readiness tools to address the mode of operation where these incidents occur. Sites then implemented the program using the tools applicable to their needs.

Culture. The first group of causes centered on the knowledge of an operator’s responsibility for energy control. In some instances, a site had failed to formally document its expectations for operator line-up. In other cases, operators had received initial training on proper line-up technique but never any reinforcement of the concept; refresher and on-the-job training ignored the topic.

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